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Jin-Feng Qi,Xiang-Yu Wang,Hua Zhang,이정희 한국식품과학회 2014 Food Science and Biotechnology Vol.23 No.4
Incorporation of an eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) moiety into diacylglycerol(DAG) oil using lipase-catalyzed esterification was optimizedusing an ethyl ester form of EPA/DHA. A response surfacemethodology (RSM) was used to optimize reactionparameters (time, temperature, and substrate mole ratio) forincorporation of DHA and EPA into DAG oil. Predictivemodels for DHA+EPA contents of DAG and the amountof DAG produced after esterification were adequate andreproducible. DHA+EPA contents of DAG significantlyincreased with reaction time and substrate mole ratio(p<0.05). In contrast, the reaction temperature negativelyaffected the amount of DAG after esterification. Synthesisof DHA+EPA-enriched DAG was optimized for a maximumDAG content with the highest DHA+EPA content, inwhich 630.0 mg of DAG containing 34.8% DHA and EPAwas predicted using the RSM model. The optimal reactionconditions were predicted at 20.6 h, 57.9 and a DHA/EPAenrichedethyl ester: DAG oil ratio of 2.5:1.
Qi‑Lei Dai,Kun Li,Kai‑Ren Meng,Zhou Fang,Wen Chen,Tian‑Bao Yang,Chi Feng,Jin‑Ming Wu,R. D. K. Misra 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.4
Advanced automotive industries generate large demand for the next generation of high strength and high toughness springsteels. Vanadium-containing 55SiCrV spring steels subjected to rapid-induction heating treatment can fulfil such requirements. However, the effect of vanadium microalloying under online rapid-induction heat treatments is rarely reported. Acomparative study of the microstructure and tensile properties of 55SiCr and 55SiCrV spring steel wires subjected to a novelonline rapid induction heat treatment has been demonstrated herein. It is found that the tensile strength of the 55SiCr springwire decreases with the decrease in the wire speed in online rapid-induction heating, and the plasticity increases. Whereas,the tensile strength of the 55SiCrV steel wire increases with the decrease in the wire speed with the retained high plasticity,which is attributed to the strengthening effect of the dislocations. Through the optimized rapid-induction heating/coolingthermal cycles and intermediate-temperature tempering treatment, the tensile strength of the 55SiCrV steel wire approaches2106 MPa with total elongation of 9.7%. Compared with the 55SiCr spring steel, the addition of V in 55SiCrV spring steelchanges the strengthening and toughening mechanisms via the grain refinement and enhancement in the hardenability andtempering resistance. The finely dispersed V-containing secondary phases are rarely found in the matrix, which indicates thatthe precipitation effect stemming from the addition of V is not the dominant strengthening factor in the online rapid-inductionheat process. The proposed novel online rapid-induction heat treatment provides a promising pathway for the mechanicalproperty improvement of the spring steel.
QI-HUI SHEN,YAN LIU,XI YU,XIAO-YANG LIU,MING-QIANG ZOU,JIN-FENG LI,JIAN-GUANG ZHOU 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2012 NANO Vol.7 No.6
II?VI Semiconductor nanocrystals (NCs) with tunable visible emission, such as CdS, CdSe and CdTe, were synthesized in aqueous solution using thiols as capping molecules. Hydrazine was found to promote the growth of NCs through a special mechanism. In only a few hours, the synthesis process was completed at room temperature. Under moderate conditions, the capping molecules not only changed the growth rate of NCs simply by varying the concentration, but also altered the spectral properties of NCs. The capping molecules with amino groups were propitious to the growth of CdS NCs, whereas the kinetic growth of CdS NCs was more a®ected by the surface passivation e±ciency of NCs than by steric hindrance in the system. The fastest growth of the CdS NCs was achieved when glutathione was used as a capping molecule, while the emission of CdS and CdSe NCs were shown to remain steady and tunable using the same capping molecule. The growth rate of 3-mercaptopropionic acid-capped CdS and CdSe NCs slowed down signi¯-cantly, while CdTe NCs were obtained with excellent emission properties when capped with the same molecule. Furthermore, our approach will also be useful for the study of the kinetic growth of NCs in aqueous solution.
Effects of Polymerization and Spinning Conditions on Mechanical Properties of PAN Precursor Fibers
Qi-Feng Qin,Yong-Qiang Dai,Kai Yi,Li Zhang,Seung-Kon Ryu,Ri-Guang Jin 한국탄소학회 2010 Carbon Letters Vol.11 No.3
PAN precursor fibers were produced via wet-spinning process, and effects of polymerization and spinning processes, especially the stretching process, were investigated on mechanical properties and micro-morphologies of precursor fibers. An increase in molecular weight, dope solid and densification and a decrease in surface defects were possible by controlling polymerization temperature, the number of heating rollers for densification and the jet stretch ratio, which improved the mechanical properties of precursor fibers. The curves for strength, modulus, tensile power and diameter as a function of stretch ratio can be divided into three stages: steady change area, little change area and sudden change area. With the increase of stretch ratio, the fiber diameter became smaller, the degree of crystallization increased and the structure of precursor fibers became compact and homogeneous, which resulted in the increase of strength, modulus and tensile power of precursor fibers. Empirical relationship between fiber strength and stretch ratio was studied by using the sub-cluster statistical theory. It was successfully predicted when the strengths were 0.8 GPa and 1.0 GPa under a certain technical condition, the corresponding stretch ratio of the fiber were 11.16 and 12.83 respectively.
Characterization of a Novel cry1-Type Gene from Bacillus thuringiensis subsp. alesti Strain LY-99
Qi, Xu Feng,Li, Ming Shun,Choi, Jae-Young,Roh, Jong-Yul,Song, Ji Zhen,Wang, Yong,Jin, Byung-Rae,Je, Yeon-Ho,Li, Jian Hong Korean Society of Sericultural Science 2009 International Journal of Industrial Entomology Vol.18 No.1
B. thuringiensis strain LY-99 belonging to subsp. alesti (H3a3c), was isolated from Chinese tobacco warehouse and showed significantly high toxicity to Plutella xylostella. For the identification of the cry1-type genes from B. thuringiensis LY-99, an extended multiplex PCRrestriction fragment length polymorphism (PCRRFLP) method was established by using two pairs of universal primers based on the conserved regions of the cry1-type genes to amplify around 2.4 kb cry1-type gene fragments. Then the DNA fragment was cloned into pGEM-T Easy vector and digested with EcoRI and EcoRV enzymes. Through this method, a known cry1-type gene was successfully identified from the reference strain, B. thuringiensis subsp. alesti. In addition, the RFLP patterns revealed that B. thuringiensis LY-99 included a novel cry1A-type gene in addition to cry1Aa, cry1Ac, cry1Be and cry1Ea genes. The novel cry1A-type gene was designated cry1Ah2 (Genbank accession No DQ269474). An inverse PCR method was used to amplify the flank regions of cry1Ah2 gene. Finally, 3143 bp HindIII fragment from B. thuringiensis LY-99 plasmid DNA including 5' region and partial ORF was amplified, and sequence analysis revealed that cry1Ah2 gene from LY-99 showed 89.31% of maximum sequence similarity with cry1Ac1 crystal protein gene. In addition, the deduced amino acid sequence of Cry1Ah2 protein shared 87.80% of maximum identity with that of Cry1Ac2. This protein therefore belongs to a new class of B. thuringiensis crystal proteins.